Okay, looks like my original expectation with SC export was not correct. AFAIK when you export intra-day data its supposed to be GMT/UTC, irrespective of your data source (exchnage) or local time zones. (Source: http://www.sierrachart.com/index.php?l=doc/doc_ImportExport.html#Notes)
However when I check the exported txt file, I can see that the time stamps are in PST. I exported the file at 12:53 PST the last bar in the file is time stamped 04/14/2013, 00:53:54, that's PST.